Deep in the Bavarian region of Germany, paleontologists have uncovered an ancient world frozen in time. At a site called Hammerschmiede, they’ve found fossils from 11.6 million years ago, dating from a period called the Miocene. Among the treasure trove of fossils, carnivorous mammals take center stage, revealing an extraordinary variety of species that once roamed the region. But, notably, among these fossils, is also a species called Kretzoiarctos beatrix — considered by paleontologists to be the oldest ancestor of the modern giant panda.

Kretzoiarctos beatrix was smaller than modern brown bears but weighed more than 100 kilograms. The teeth of these species are very similar to those of pandas, which feed almost exclusively on bamboo. But K. beatrix may have munched on more than just leaves. Its diet, say the authors of a new study, looked a lot like that of omnivorous bears.

“Today’s giant pandas are part of the group of carnivores in the zoological taxonomy, but in fact, they live exclusively on plants. They’ve specialized in a hard vegetable diet, specifically of bamboo,” reports Dr. Nikolaos Kargopoulos from the University of Tübingen and University of Cape Town, the lead author of the new studies. It is scientifically interesting how these pandas — who were originally carnivores — adapted to such an extreme herbivorous diet, Kargopoulos added.

Panda Teeth

In the new research, scientists carried out both a macro- and a micromorphological analysis of K. beatrix teeth. The macro analysis shows how the teeth change depending on their role in processing food, giving a hint at what the animals would eat in general. The micro analysis can reveal scratches and pits caused by interaction with various food particles. “The characteristics of these surface changes can give clues to the dietary habits of an animal in a short period before its death,” says Madelaine Böhme from the Senckenberg Centre for Human Evolution and Palaeoenvironment at the University of Tübingen, author of the new study.

The analysis also compared teeth with those of pandas, brown bears, polar bears, South American spectacled bears, as well as extinct giant pandas. They concluded that the panda ancestor did not specialize in hard plants like today’s panda, nor was it a carnivore like polar bears. If anything, its teeth look like those of the omnivirous brown bear, containing both plants and animal elements.

“These results are important to our understanding of the evolution of bears and the development of herbivory in giant pandas. It turns out that Kretzoiarctos beatrix, the oldest of the pandas was a generalist. Specialization in the panda’s diet only came about late in its evolution,” says Böhme.

The Miocene Carnivores of Bavaria

The Hammerschmiede site has yielded fossils of 28 carnivorous species, spanning a variety of families. This level of diversity is exceptional for the Miocene epoch in Europe. But what made Hammerschmiede such a hotspot for carnivorous mammals? Apparently, this was an ecosystem with ample resources, capable of supporting predators ranging from weasel-like animals that weighed less than a kilogram, right up to large hyaenas and saber-toothed tigers weighing over 100 kilograms.

“Such a diverse population of predators is not only extremely rare in fossil terms; there’s hardly any modern habitat with a similarly large number of species,” says Böhme. This diversity of species at the top of the food chain indicates that the ecosystem of the Hammerschmiede must have worked extremely well. In fact, there are even species that thrived side-by-side, despite occupying very similar niches, the researcher says. “For example, there are four different otter-like animals of approximately the same size and type of diet. Normally, they would compete for the natural resources in their environment. But it seems that the resources of the Hammerschmiede were rich enough to meet the needs of every species.”

The carnivores of Hammerschmiede ranged from tiny species under 1 kg to massive predators over 100 kg. The larger carnivores, such as a giant amphicyonid (a bear-dog species), K. beatrix, and a species of seal, could weigh up to 200 kg. This wide range of body sizes is a good indicator of a highly stratified ecosystem, with small, medium, and large carnivores hunting different types of prey or scavenging different remains.

For example, a species like Pseudaelurus quadridentatus, a felid that weighed around 50 kg, could target prey too large for smaller carnivores but too small for the giant amphicyonid. At the same time, small carnivores like Viverrictis modica (a type of viverrid) would have specialized in hunting small prey such as insects, leaving the larger prey to bigger carnivores.

A Thriving Ecosystem For Carnivores

“Their respective primary sources of food were very varied: there were pure carnivores such as the saber-tooth tiger, fish-eaters like the otter, and bone-eaters such as the hyaena. A few other species like the panda and the marten fed opportunistically on plants and animals of various sizes,” Kargopoulos says.

These new species were also very different in their choice of habitat. “The otter-like animals were good swimmers; bears, hyaenas and others stayed on the land or lived in burrows like the skunks. A strikingly large number of species were tree-climbers like the marten, cat-like animals, genets and red pandas,” explains Kargopoulos.

The locomotion patterns of these carnivores also reveal fascinating adaptations to their environment. This variety in locomotion shows that Hammerschmiede’s landscape was likely diverse, with forested areas, open plains, and river systems providing habitats for animals with different movement styles. Arboreal species could have thrived in the forest canopy, while terrestrial predators roamed the ground, and semi-aquatic species hunted along the water’s edge.

Interestingly, there are signs that the ecosystem was in a state of transition. While some species found at Hammerschmiede, such as Laphyctis mustelinus and Lartetictis dubia, are typical of the Middle Miocene. Others, like Semigenetta grandis, are more commonly found in Late Miocene environments. This mix of faunal elements suggests that Hammerschmiede existed during a period of ecological change, possibly linked to climate shifts and the gradual disappearance of certain species as new ones took over.

Journal Reference: Nikolaos Kargopoulos, Juan Abella, Alexander Daasch, Thomas Kaise, Panagiotis Kam-pouridis, Thomas Lechner, Madelaine Böhme: The primitive giant panda Kretzoiarctos beat-rix (Ursidae, Carnivora) from the hominid locality of Hammerschmiede: dietary implications. Papers in Palaeontology, https://doi.org/10.1002/spp2.1588